MUNSTER lost for the second time on the trot at Musgrave Park, but injuries to Conor Murray, Mike Sherry and Stephen Archer will worry Rob Penney more ahead of next weekend's Heineken Cup trip to Edinburgh
Rhys Patchell slotted home a free-kick from the right after just nine minutes to give the Blues a 3-0 lead.
Shortly afterwards, following another powerful drive from Penney's side, Welsh referee Nigel Owens awarded Munster the penalty – their third from that source – which O'Gara dispatched on the day he picked up a record 233rd Munster cap.
And O'Gara was proving equally influential kicking from hand, as on every opportunity he pinned Cardiff deep in their own territory.
But all the kicking on display was not as accurate, as both sides treated the Musgrave Park faithful to long spells of aimless bombardments as half-time approached.
After losing Murray early on to a blood injury, the Munster coach would have been horrified to see first-choice hooker Sherry limp off midway through the first half, especially with next weekend's crunch Heineken Cup tie away to Edinburgh on the horizon.
After going in at half-time at 3-3, it was the visitors who got off to the better restart with a splendidly worked try from Owen Williams. The Munster defence had looked solid all night, but after a series of pick and goes, Jamie Roberts put Williams through the gap as the winger cut a viscous line through the heart of Munster.
Patchell added the extras with ease to stretch Cardiff's lead out to 10-3, but straight from the restart, Munster hit back with an O'Gara penalty.
As the fog descended on the Cork venue, the error count increased from the home side as knock-ons across the back-line blighted some positive work on the front foot.
Ten minutes from time, Cardiff wrapped up the win when Copeland pounced on Duncan Williams' fumble and cantered in for the try.
Scorers – Munster: R O'Gara 2 pens Cardiff Blues: O Williams, R Copeland tries; R Patchell 2 cons, 1 pen
Munster: F Jones; D Howlett, K Earls (C Laulala 59), J Downey, D Hurley (I Keatley 60); R O'Gara, C Murray (D Williams 15 blood); D Kilcoyne (W du Preez 74), M Sherry (S Henry 24), S Archer ( BJ Botha 62); D Foley (B Holland 58), D Ryan; T O'Donnell (CJ Stander 62), S Dougall, J Coughlan.
Dragons: J Tovey (L Halfpenny 53); O Williams, R Smith, J Roberts, H Robinson; R Patchell, L Jones (A Walker 62); S Hobbs (P Tamba 69), R Williams (K Dacey 69), B Bourrust (S Andrews h-t); B Davies, L Reed (J Down 57); J Navidi, S Warburton, R Copeland (L Hamilton 70).
Referee: N Owens (WRU)